Process for the production of spinning jets



Feb. 7, 1950 3. SCHNYEIDER 2,496,961

PROCESS FOR THE PRODUCTION OF SPINNING JETS Filed Oct. 15, 1946 INVENTOR. GEORGE SCHNE I D'ER Patented F ch. 7, 195( PROCESS FORTHE PRODUCTION OF SPINNING JETS George Schneider, South Orange, N. J., assignor to Celanese Corporation of America, a corporation of Delaware Application October 15, 1946, Serial No. 703,326

This invention relates to the production 'of spinning jets employed for the prepa'rationof artificial filamentary materials by extrusion operations and relates more particularly to the production of spinning jets provided with orifices of extremely fine diameter. d

An object of this invention is the provision" of a novel process for the production of spinning jets of a relatively inexpensive material, which jets are resistant to corrosion or attack by the spinning solution and the spinningbaths employed for filament-forming extrusion operations.

Another object of this invention is the production of spinning jets containing a plurality of extremely fine orifices and adapted to be employed for the formation of artificial fila mentary materials of very fine denier by extrusion operations.

Yet another object of this invention is to provide a process for the production of spinning jets which yields jets having orifices of extremely fine diameter without resorting to the very delicate and precise machining, drilling and polishing operations heretofore employed. v

A further object of this invention is the provision of an electrolytic plating process for the production of spinning jets having jet holes or orifices of any desired diameter.

Other objects of this invention will appear from the'following detailed description. r

In the drawing, the figure is a view in perspecfive, on an enlarged scale, of aspinning jet or spinneret comprising a shaped hollow cup 1 provided with a lip 2, the lower surface of said cup 1 containing a plurality of orifices 3 of extremely fine diameter through which the filament-form ing material is extruded.

Artificial filaments are usually formed by extruding a filament-forming material under pressure through the multiple orifices of a spinneret and then passing the filaments thus formedinto a setting or coagulating medium. The spinneret is usually made of a suitable metal, and the number of filaments formed by extrusion cor responds to the number of orifices present in the jet. The metal employed must be resistant to corrosion or attack by the spinning solution extruded through the orifices as well as resistant to the corrosive effect of the spinning bath in which the filaments are coagulated. In the spin ning of viscose, spinning jets of precious metals or precious metal alloys are employed whereas in the spinning of filaments having a basis of an organic derivative of cellulose, spinning jets of stainless steel are preferred since they. do not involve such a large capital outlay. Of'course,

4 Claims. (Cl. 204-24) 2 y precious metals may also be employed in the spinning of organic derivatives of cellulose. After the filaments have set they are gathered to form a yarn and the yarn is then collected on 9, bobbin or other suitable .support to form a yarn package. Although some reduction in denier maybe produced by stretching the filaments as they are formed, the denier or fineness of the filaments comprising the yarn is largely controlled by the diameter of the orifices in the spinning jet through which the filament-forming material is extruded. The finer the denier of the individual filaments, the softer and more pliable is the yarn and the fabrics woven there'- from, making the production of filaments of finer deniers an important objective in the production of artificial textile materials.

The manufacture of spinning jets capable of producing the very desirable fine denier filaments is a slow and time-consuming operation involving the application of an unusual degree of care and skill. Although the orifices are of such fine diameter that they can scarcely be seen by the unaided eye, they must each be smoothly bored,

of uniform diameter and properly spaced about the jet to avoid any contact between the shaped filaments before thelatter are solidified in the setting medium. To produce such spinning jets has heretofore required a sequence of very delicate operations which include the countersinking and drilling of the orifices followed by a manual finishing of the jet faces and the drilled orifices to remove the burr which is present and to polish the bore of the orifices so that they will be smooth and of uniform size. The difiiculties involved in the commercial production of spinning jets by the above process serve to limit the minimum practical diameters to which the orifices can be drilled and finished economically. Going beyond this minimum diameter has not been commercially feasible and, consequently, the production of artificial filaments of finer denier was not possible due to the unavailability of spinning jets having orifices of the necessary small diameter.

I have'now found that spinning jets containing smooth, uniform orifices of any desired diameter may be obtained in a rapidand economical manner it spinning jets, provided with relatively fine orifices of a diameter greater than that ultimately desired in said jets, are the cathode of an electrolytic plating bath and "current then allowed to flow through the bath so as to cause the deposition of metal on said jets. Surprisingly enough, not only do the external surfaces of said jets receive the metal deposited by the flow of current through the electrolytic plating bath, but the inner surfaces of the orifices themselves, in spite of their very fine diameter, also receive a deposition of metal. By maintaining the fiow of current and continuing the plating operation for a sufiicient period of time, the layer of metal deposited in said orifices may be continuously increased in thickness and the final diameter of said orifices reduced to as small a dimension as desired. Thus, spinning jets originally having orifices of a drilled and finished diameter of 0.05 millimeter or more may be rapidly and eiiiciently reduced in size to. a diameter of 0.02 millimeter or less, a dimension considerably below that which can be attained emciently by even the most painstaking opera-.

tives. By my novel process not only are the jet orifices so reduced in diameter as to enable filaments of extraordinarily fine denier to be produced by the usual spinningoperationsbutthe fine orifices so produced are renderedsmooth, well-rounded and free from any surface irregularities making possible increased spinning speeds.

The spinning jet treated in accordance with my novel process may be formed of any suitable metal or alloy such as, for example, stainless steel of any composition, nickel, platinum, goldplatinum, gold-rhodium, etc. The metal plated on said spinning jets may be any suitable metal forming a desirably hard, dense and adherent layer when deposited from an electrolytic plating bath. Suitable metals which may be deposited on the internal and external surfaces of the spinning jets to reduce the diameter of the 1'- orifices are, for example, gold, silver, platinum, copper, nickel, palladium, zinc, cadmium, tin or cobalt, but excellent results are obtained when depositing chromium as the plating on the surfaces of said spinning jets, the latter being especially valuable due to its corrosion-resistant properties. When a base metal spinnin jet, e. g. one of stainless steel, is plated with chromium, for example, the use of corrosion resistant precious metals and precious metal alloys is eliminated. l a

Thus, in the case of chromium plating baths, optimum results are obtained employing aqueous baths containing from 100 to 400 grams of chromic acid per liter of water, the baths being acidified with from 1 to 4 grams per liter of concentrated sulfuric acid. To produce the desired deposition, when employing said plating bath with a satisfactory throw of the chromium to the very fine internal surfaces of the spinning jet, current densities of 100 to 500 amperes per square foot are satisfactory with the plating bath being maintained at temperatures of about 35 to 55 C. and, preferably, about f15 C. during the plating operation; The anod may-be steel or lead and the voltage necessary is usually about 5 to 10 volts. In accordance with my process, specially shaped anodes are not necessary to achieve the necessary throw. Th platin action is continued until the thickness of the metal deposited on the external surfaces of the jet and within the orifices has reduced-the latter to the desired fine diameter. 1 7

In order further to illustrate my-novel process, but without being limited thereto, the following example is given:

Example A stainless steel spinning jet containing .42 orifices each of 0.052 mm. in diameter is immersed 4 as the cathode in an aqueous plating bath containing 125 grams per liter of chromic acid and 1 gram per liter of concentrated sulfuric acid. Employing a lead anode, a voltage of 6 volts and a current density of about 250 amperes per square foot with the bath at 45 C., the orifices are each reduced to a diameter of 0.028 mm. after about one hour. The internal surfaces are smooth, hard and highly resistant to scratching. By continuing the plating operation for a longer or shorter period of time, the orifices may be altered to any desired diameter. Furthermore, the plated spinning jet is highly resistant to corrosion.

While my invention has been more particularly described in connection with the production of spinning jets provided with orifices of fine diameter, it may also be employed for the production of various other commercial units wherein orifices ofvery fine diameter are desired.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for the production of spinning jets having a plurality of extremely fine orifices adapted for filament-forming operations, which comprises forming in a spinning jet of a conducting material a plurality of orifices having a diameter of about 0.052 millimeter, immersing said spinning jet in an electrolytic plating bath comprising an acidified solution of chromic acid, and electroplatin th internal and external surfaces of said spinning jet with a layer of chromium until the orifices are reduced to a diameter of about 0.028 millimeter.

2. Process for the production of spinning jets having a plurality of extremely fine orifices adapted for filament-forming operations, which comprises forming in a stainless steel spinning jet a plurality of orifices having a diameter of about 0.052 millimeter, immersing said spinning jet in an electrolyticplating bath, and electroplating the internal and external surfaces of said spinning jet with a layer of metal until the orifices are reduced to a diameter of about 0.028

millimeter.

' 3. Process for the production of spinning jets having a plurality of extremely fine orifices adapted for filament-forming operations, which comprises forming in a stainless steel spinning jet a plurality of orifices havinga diameter of about 0.052 millimeter, immersing said spinning jet as the cathode in an electrolytic plating bath comprising a solution of from to 400 grams per liter of chromic acid acidified with 1 to 4 grams per liter of concentrated sulfuric acid, and plat.- ing the internal and external surfaces of said spinning jet with a layer of chromium employing a current density of 100 to 500 amperes per squarefoot and a lead anode until the orifices are reduced to a diameter of about 0.028 millimeter.

4. Process for the production of spinning jets having a plurality of extremely fine orifices adapted for filament-forming operations, which comprises forming in a stainless steel spinning jet a plurality of orifices having a diameter of about 0.052 millimeter, immersing said spinning jet as the cathode in an electrolytic plating bath REFERENCES CITED The following references are of record in the 15 file of this patent:

UNITED STATES PATENTS Number Number Name Date Stresau Feb. 10, 1931 Cleveland July 6, 1937 Norris Dec. 24, 1940 Atwood May 19, 1942 Orton July 4, 1944 Jones Nov. 7, 1944 Atwood Mar. 6, 1945 Wick Jan. 15, 1946 FOREIGN PATENTS Country Date Great Britain of 1904 Great Britain of 1920 Germany June 15, 1928 

